Budget A/C System... Anybody try this?
I'm doing a budget A/C install on my house (1600 S.F) since money is tight and figure it's an excuse to play around a bit.
That being said, Heres what I have:
Take out: 5 ton 10 SEER AMANA unit which wil have a new 4 ton Copeland Scroll installed as well as an 825 RPM C.F.M
I'm thinking a 75,000 BTUH furnace with either a 4 ton 13 seer evap or 5 ton 10 seer evap with TXV depending on what I come across. My hopes is that even though it is an older unit it will still be reasonably efficient given the larger condensor size and large evaporator to match.
Has anyone tried something similar to this and if so how did it work out? Any thoughts on this?
Sounds like you're trying to engineer a system on a paper napkin.
Money may be tight...but you may end up spending a lot more thinking you're saving a little.
If you're in the trade and don't mind nursing along your own frankensystem, you should already know it may not be a smooth watch.
On a simple straight A/C system it isn't rocket science. A TXV eliminates a lot of issues. BTW, yes I have done exactly what you described. Different size, different brands, but same thing.
Last edited by hvacrmedic; 03-18-2008 at 02:08 AM.
Sounds like a lot of home owner questions to me.
Originally Posted by The Tucson Tech
Sounds like a lot of guess work. Not enough thought to why.
You want to build this for your house ok. I can understand the financial reasoning, and the desire to tinker.
When you sell this house, are you going to put a matched system in, so the new owner doesn't have a play thing for heating cooling system.
Why are you slowing the blower, how did you determine the proper CFM air flow for the OD unit.
Are you going to check capacity when its in an running.
The surface area of the condensor on this unit is roughly 34 sq ft. as a two pass design. A 13 SEER 4 ton Rheem or York System has approximately 23 Sq ft of 1 pass condensor surface. Both York and Rheem are running at about 3500 CFM for the same unit. I will match these CFM numbers within reason by matching the fan blade and motor RPM accordingly.
Originally Posted by beenthere
To say that this system will be a burden on a future homeowner is not a really a fair judgement. It's a numbers game, not a mystery. I just want to make sure I have my basis covered and am not overlooking anything, thus my reason for posting on here.
Everything sounds a bit oversized to me. But its your house. If you're a homeowner and not in the biz. Good luck. I would do something else. It may or may not work, who knows. If you're in the biz, then you know the answers to the questions. If I need something, I get it at cost. I usually look for damaged or returned stuff. I personally wouldn't do the frankensystem. My boss put a 2 1/2 ton scroll in a 5 ton body for craps and grins about 2 years ago. It made it a summer and it still runs, he just didn't like the way it did, he had to overcharge it to get it to cool. Needless to say, he spent the money and did it right about a month ago.
I don't think you can blame the not cooling problem on the larger coil. Maybe he didn't upsize the piston or install a TXV?
Originally Posted by bmathews
You wouldn't upsize the piston when installing a 2.5 ton compressor in a 5 ton condenser.
To the OP.
Its more then a numbers game if you seel the house with this thing still installed.
When a service tech comes out and sees the mismatch.
First thing he'll say to the new HO, is you got a f-ed up system.
makes you look bad.
Projects like this can be good learning labs. But should never be left for someone else later down the road.
Getting your air flow over the OD coil, will still be a lot of guess work. A double row coil has higher resistance then the single rows.Fan blade selection will take a couple guesses.
I was refering to the 2,5 ton compressor in a 5 ton evap.
You wouldn't use a 5 ton piston on the evap..
Possibly by the time this beast is assembled ,T T T (The Tuscon Tech) will have enough posts to get in the Pro sections. It would be interesting to see what this creation does. Keep us posted.
I stand by my original statement, there's no magic here. It's a numbers game, short and simple. System pressures are key items for system design. I've done my homework on this and coil sizing and airflow will be adjusted to set proper pressures. With that being said, if you have good pressures and a proper split whats left? I would like to think that any good tech would know how to identify a system similar to this and service it accordingly without selling the customer a new system based on the attitude of " I don't understand how it could work, it must not." I'm not sure that this unit will be in place when I sell the house, I do however think that there are a few people on this board smart enough in this trade who understand the fundamentals enough to be completely content with this system if they came across it.
I will be sure to post my results with this system in the weeks to follow. Hopefully in the "Pro Section". I still need to round up a furnace and coil however and with the weather bouncing around I will probably slack a bit on the install rush... ; ) I'll keep ya guys posted...